The Design of Diagnostic Medical Facilities where ... - ResearchGate

Walls are generally shielded to full height from the floor to the underside of the ceiling slab above (not to the
false ceiling), unless the protection in the ceiling extends well beyond the X‐ray room. This is to protect not
only the room directly above but also the adjoining rooms above, which would otherwise be obliquely
irradiated. The join between the wall and the ceiling must be adequately shielded (Appendix E). If the X‐ray
room is adjacent to a dark room or a storage facility for CR plates, shielding to full height is required to
protect films/CR plates located on high-level shelving (NCRP, 2004).
Photo 6.1: Image of a primary beam absorber behind a vertical bucky
(Photograph courtesy of St. James’s Hospital, Dublin)
Some situations may arise where wall shielding to full height is not required. An example of this may be a
single storey building with no two storey buildings in the vicinity. Other examples include low exposure
applications (e.g. mammography or DXA). In these instances, the height of the wall shielding required must
be determined by the RPA and it may be sufficient to shield to a height of 2 m from the outside ground.
However, care must be taken when walls are not shielded to full height as situations may change and records
of the shielding specifications may not always be available or accessible in the future. Therefore walls should
be permanently labelled with the lead equivalence thickness.
Occasionally where lead lined panelling is used, the wall shielding is specified and installed to a height of 2 m,
where the panelling may extend to 3 m. In such cases it is very important to ensure that the leaded part of
the panelling is installed the correct way up as the other third of the panel is unshielded (NCRP 2004).
Reftrofitting at a later stage can be very expensive and troublesome.
Gypsum plaster or 100 mm medium density concrete blockwork may be sufficient for shielding mammography
rooms. Additional advice on the engineering of walls for diagnostic facilities is available in NHS (2001).
6.3.2 Floors and ceilings
Imaging facilities are frequently located on the ground floor of hospitals. Floor shielding is not necessary if
there are no occupied basements or under floor service corridors, provided that the shielded wall extends the
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The Design of Diagnostic Medical Facilities where Ionising Radiation is used